Bearing assembly for a wheel of a motor vehicle

ABSTRACT

The invention relates to a bearing assembly in an especially drivable wheel hub at the associated wheel carrier of a motor vehicle. It comprises a double row angular ball bearing whose outer bearing ring is first produced as one part and is then divided by breaking it apart. The special arrangement and design of the joint ensures a close connection between the two bearing ring parts and permits a method of assembly allowing the two bearing rows to be filled with a larger number of rolling members.

DESCRIPTION

The invention relates to a bearing assembly of an especially drivablewheel hub at the associated wheel carrier of a motor vehicle, having adouble-row roller bearing whose outer divided bearing ring has beenprovided for being fixed to the wheel carrier and whose innersingle-part bearing ring forms one unit with the wheel flange forattaching the vehicle wheel.

In the case of bearing assemblies with undivided bearing rings the twobearing tracks for the rows of rolling members are provided at adistance from one another in the bearing ring. The advantage of such adesign is that the two bearing tracks can be produced accurately, forexample it is possible to observe an accurate distance between the twotracks. This is achieved by machining the two tracks in a clampingdevice, which means that they are also at an identical distance from theaxis of rotation. With bearings, dimensional deviations lead to noiseand/or a reduced service life. However, the disadvantage of a wheelbearing assembly with an undivided outer bearing ring and inner bearingring is that its degree of filling is reduced relative to the bearingdiameter. The degree of filling is approximately 65% of that of bearingswith divided bearing rings. However, divided bearing rings requirecentering relative to the axis of rotation and accurate machining of afurther radial face in order to ensure an accurate distance between thebearing tracks.

A wheel bearing assembly for motor vehicles with single-part bearingrings is known from DE-OS No. 2260413 for example, whereas a wheelbearing assembly with a divided outer bearing ring is disclosed in DE-OSNo. 2654607. From the latter publication it can also be seen that a rowcan only be filled up to 50% with rising members in order to permitassembly.

A further disadvantage of divided outer bearing rings of the discloseddesign is that the centering means have to accommodate the forcesoccurring for example when negotiating curves or upon impact, whenhitting a curbstone for instance, such forces acting on the bearing inthe form of a tilting moment in that the rings tend to be displacedrelative to each other. In order to avoid negative influences onconcentric running and the service life, more sophisticated productionmethods and higher production expenditure are required to achieve thenecessary accuracies for the centering means.

In view of the above it is the object of the invention to provide awheel bearing assembly which retains the advantages of the design with adivided outer bearing ring in respect of the degree of filling and loadbearing capacity, but which on the other hand is characterised bysimplified production methods and reduced production expenditure withoutadversely affecting concentric running and service life, and ensures ahigh resistance against tilting moments.

In accordance with the invention the objective is achieved in that theouter bearing ring is divided by breaking it apart and the inner bearingring is integral with a component of a driving joint provided fordriving a vehicle wheel or is connected to it via teeth. It is possibleto break the outer bearing ring in such a way that two rings areproduced, with breaking taking place in the radial plane containing theaxis of rotation of the roller bearing.

Breaking may also take place in such a way that the bearing ring isdivided axially into two parts, but the joint extends at an anglerelative to the axis which deviates from 90°. In the first case, the twobearing ring parts produced by breaking each contain one half of thecircumferential extension of the two outer bearing tracks. In the secondcase, the two bearing ring parts each contain the full circumferentialextension of an outer bearing track. Furthermore, it is also possible toburst the outer bearing ring only in one place of its circumferentialextension so that a slot occurs when it is bent open.

The advantage of this design is that during the production process theouter bearing ring is still in one part and contains both bearing trackswhich may be machined in a clamping device. Due to the breaking methodand the special position of the joint occurring in the process, a closeconnection is produced when rejoining the bearing ring because in theregion of the joint there are irregularities which be can broughttogether in only one position of the two ring parts and result in anengagement of the surface parts. This design helps to achieveself-centering, there is no need for special centering faces orcentering measures and furthermore, the joint, due to the closeform-fitting connection, helps to receive any tilting moments that mightoccur.

In a further embodiment of the invention provision has been made for theouter bearing ring to be achieved in a holding ring in order to achievea pre-assembled unit. The holding ring has been provided with a radiallyextending stop face contacted by a corresponding radial face of theouter bearing ring and an inner face for receiving the outer face of theouter bearing ring, with the inner face of the bearing ring coveringonly part of the axial extension of the outer face of the outer bearingring.

In order to facilitate final assembly of the bearing unit in the vehicleprovision has been made for the holding ring and the outer bearing ringto be connected to each other by assembly bolts. In this way, the wheelbearing unit forms a pre-assembled system which needs to be attached tothe wheel carrier of the vehicle only.

In a preferred embodiment, the outer bearing ring, with its outer faceand at least part of its radial extension, is received in a bored stepof the wheel carrier and, via the holding ring, is connected eitherdirectly or indirectly to the wheel carrier by fixing bolts.

Breaking the outer bearing ring apart becomes particularly easy if thejoints extend through the radial plane containing the bores forreceiving the fixing bolts.

To produce the outer bearing ring of the bearing assembly, the inventionprovides a process according to which the outer bearing ring in a softcondition is first machined in a non-chip forming way to itsfinish-dimension before grinding, then the outer bearing ring, on itsinner and/or outer circumferential face, is provided with notches inthose regions from which the broken joints initiate, and subsequently,the outer bearing ring is hardened and ground to its finish dimensionsand after grinding it is broken apart by applying pressure which exceedsthe limit of elastic deformation. By providing notches it is possible toensure a specific extension of the joints. In case the joints extendthrough the tracks the invention provides for the tracks, afterbreaking, once more to undergo precision machining, especially honing.

Preferred embodiments of the invention are illustrated in the drawingwherein

FIG. 1 is a longitudinal section through one half of a first embodimentof the bearing assembly

FIG. 2 is a longitudinal section through a second embodiment in the caseof which the outer bearing ring has two joints

FIG. 3 is a longitudinal section through an embodiment with the outerbearing ring divided into two parts in accordance with FIG. 2, with theunit being shown in the upper half in an assembled condition and in thelower half prior to assembly

FIG. 4 is a lateral view belonging to section to FIG. 3, shown partiallyin section

FIG. 5 is a longitudinal section through an embodiment with a modifiedholding ring and an outer bearing ring having one joint only

FIG. 6 is a partial illustration of the outer bearing ring, the holdingring and the track of the inner bearing ring of FIG. 5

FIG. 7 is a lateral view belonging to FIG. 6

FIG. 8 shows an embodiment to FIG. 5 in the case of which the drivingjoint is connected to the inner bearing ring by teeth.

FIG. 1 shows one half of the wheel bearing unit attached to the wheelcarrier 11; the wheel hub 1 has been provided with a wheel flange 2which is integral with it and which serves to attach the brake disc andthe vehicle wheel for example. The inner bearing ring 3 also forms partof the wheel hub just as the outer part 13 of the constant velocityuniversal joint 22 serving to drive the wheel flange 2 and thus thevehicle wheels. The driving joint 22 is not illustrated in detail, onlythe outer joint member 13 is shown. The rotary motion coming from theengine and transmission is transferred via a joint at the transmissionend to an intermediate shaft and via the joint 22 at the wheel end toits outer part 13 and the wheel flange 2.

The part of the wheel hub 1 forming the inner bearing ring 3 bas beenprovided with two bearing tracks 5 arranged at a distance from oneanother around the bearing axis x-x. The plane extending at a rightangle relative to the bearing axis x-x between the two bearing tracks 5has been given the reference symbol y-y. The bearing tracks 5 containrolling members 20 which also roll in corresponding bearing tracks 6 ofthe outer bearing ring 4.

The bearing tracks 5 in the inner bearing ring 3 and the bearing tracks6 in the outer bearing ring 4 are arranged in such a way that the planeextending through their points of contact with the rolling members 20extends at an angle relative to the axis of rotation x-x, intersectingthe plane Y-Y in the direction towards the bearing axis x-x. it is adouble-row angular contact ball bearing. The rolling members 20 are heldin a joint cage or in a cage 8 for each bearing row. The outercircumferential face 19 of the outer bearing ring 4 is received in abored step 12 of the wheel carrier 11 of the motor vehicle. It isreceived on part of the axial extension A of the outer bearing ring. Theouter bearing ring 4 is attached to the wheel carrier 11 by fixing bolts15. The outer bearing ring also comprises sealing caps 10 one of whichcovers part of its circumferential face 19. The sealing caps 10 arecontacted by sealing lips of seals 9 which are also arranged at thewheel hub.

The outer bearing ring 4 has been divided into two parts. Its two ringparts 4a and 4b are produced after machining of the outer bearing ring 4and its tracks 6 and breaking it apart.

The outer bearing ring 4 is broken apart in that starting from theannular notch 33 extending across the outer circumference 19 of theouter bearing ring 4 and continuing to a further notch 34 extendingcircumferentially in the inner face of the outer bearing ring, a joint24 occurs after the application of pressure. The joint 24 is irregularand permits rejoining of the two ring parts 4a and 4b in one singleposition only. The circumferentially extending notches 33, 34 are offsetrelative to each other in respect of the axial extension A of the outerbearing ring 4.

The inner notch 34 is closer to the plane y-y than the outer notch 33.The inclined extension of the joint 24 which is due to the abovearrangement of the notches 33, 34 and which, looking at the entirecircumference, takes an approximately conical course, ensures radialcentering of the two ring parts 4, 4b relative to each other. Inaddition, this design achieves a close connection in the case ofdistortion, accommodating any lifting moments that might occur. Theinner face of the outer bearing ring contains a sealing ring 32preventing any lubricants entering the joint 24 from the bearing.

By providing the sealing cap 10 with a region which also partiallycovers the outer face 19 of the bearing ring 4 the two ring parts 4a, 4bare clamped together thereby producing one unit which can be suppliedseparately to a vehicle manufacturer and is then connected to the wheelcarrier 11 via bolts 15.

In the embodiment to FIGS. 2, 3 and 4, the outer bearing ring 4 bas beenbroken apart in two pieces across its circumference. Breaking wasachieved with the help of two notches extending parallel to the axis ofrotation x-x across the axial extension of the outer face 19 of theouter bearing ring 4. The outer bearing ring 4 has been provided with athrough-bore 16 through which the fixing bolts 15 are guided.Furthermore, the outer bearing ring 4 is partially embraced by a holdingring 7 having a cylindrical inner face 18 designed to watch the outerface 19 of the bearing ring 4.

The radial face 30 of the outer bearing ring 4 either directly contactsa corresponding stop face 17 of the holding ring or a radially extendingpart of the sealing cap 10 is arranged between them. The holding ring 7has been provided with bores 27 corresponding to the through bores 16 inthe outer bearing ring 4, through which the fixing bolts 15 are guided.The threaded ends of the fixing bolts 15 engage a correspondly threadedbore 29 in the bored step 12 of the wheel carrier 11. The other radialface 31 of the outer bearing ring 4 either directly contacts acorresponding face of the wheel carrier 11 or, preferably, the radiallyextending part of the other sealing cap 10 has been arranged betweenthem. The holding ring 7 ensures radial support of the outer bearingring 4 which, without such radial guidance, would fall apart because ofits division.

The outer bearing ring 4 is divided into two parts in the radial planE-E and comprises two joints 24, 25 which are arranged in such a waythat they are positioned in the region of the bores 16 for the fixingbolts 15. Furthermore, bores 28 are distributed across the circumferenceof the outer bearing ring for the purpose of holding assembly bolts 14which engage corresponding threaded bores in the holding ring 7, therebyproducing a pre-assembled unit preventing the two ring parts 4a, 4a ofthe outer bearing ring 4 from falling apart after installation. Theupper half of FIG. 4 shows the unit in the assembled condition and thelower half illustrates the undissembled ring part 4b before being movedinto its final position.

The cage or the cages 8 for the bearing members 20 are designed in sucha way that, for the purpose of assembly, first the seals 9 adjoining thewheel flange 2, then the holding ring 7 with the first sealing cap 10are slid on. As illustrated in the lower half of FIG. 4, the holdingring 7 is made to contact axially the wheel flange 2. Subsequently, thebaits 20 are pressed into the cages 8 and because of the design of thecages, they are held in this position. Then the two halves 4a, 4b of theouter bearing ring are introduced radially.

When the two bearing ring parts 4a, 4b have assumed the operate positionrelative to each other and to the two rows of rolling members 20, theholding ring 7 may be moved from its position towards the left towardsthe right in the direction of the outer joint part 14 via the outer face19 of the bearing ring 4. Subsequently, the holding ring 7 is bolted tothe two parts 4a, 4b of the outer bearing ring by means of assemblybolts 14 which can simultaneously act as axial holding means for thefurther sealing cap 10. When finally the sealing ring 9 is fitted, aunit for final installation into the vehicle by the vehicle manufactureris available.

The embodiment to FIG. 3 differs essentially from that of FIG. 2 in thatthe holding ring 7 covers the entire axial extension A of the outerbearing ring 4 and is held by an axially following clamping ring 21 inthe holding ring and in that there is only one joint 24.

There now follows a description of the assembly. First the sealing ring9 adjoining the wheel flange 2 and then the clamping ring 21 and theassociated sealing cap 10 are slid on. Furthermore, the cage 20 for therolling member row to the left of plane y-y and the associated rollingmembers 20 are introduced. Subsequently, the outer bearing ring 4 issaid over from the end of the outer joint part 13 so that, with itstrack 6, it rests against the rolling members 20 which have already beeninserted. Subsequently, after introduction of the cage 8, the rollingmembers 20 of the bearing row to the right of plane y-y are introducedal an angle through the gap produced by expanding the outer bearing ring4 in the region of the joint 24. In the process, the inner bearing ring3 is turned on in the circumferential direction so that each time afurther bail may be inserted into its coston through the gao. After allrolling members 20 have been inserted, the holding ring 7 is slid overthe outer face 19 of the outer bearing ring 4 and from the end of theouter joint member 13 the second sealing cap and the associated sealingring 9 are slid on.

With the embodiments to FIGS. 2 to 8, the tracks 5 and 6 in the innerbearing part 3 and the outer bearing ring 4 are arranged in such a waythat the point of intersection of the contact line of the two bearingrows of the outer and inner bearing tracks extending through the contactpoints is positioned readily outside the two bearing tracks 6 of theouter bearing ring 4. With reference to the axis of rotation x-x, thisresults in an increased basis of support for the bearing for receivingthe tilting moments.

Whereas in the embodiments to FIGS. 1 to 7, the outer joint part 13 ofthe driving joint in the form of a constant velocity universal jointprovided for driving the wheel flange 2 forms one unit with the wheelhub, the driving joint 22 in the embodiment to FIG. 8 and thus is outerjoint part 13 is separate from the wheel hub 1. However, both areconnected to each other via teeth 23 provided at the end face of thepart of the wheel hub 1 positioned away from the wheel flange 2. Theouter joint part 13 has been provided with corresponding teeth.Furthermore, the wheel hub 1 and the outer joint part 13 are securedaxial and non-rotating by a bolted connection 30 arranged in the centralbore 36 of the wheel hub 1.

The outer bearing ring of all embodiments is produced in that first, inthe soft condition, it is machined in a chip or non-chip forming way byachieving the finish-dimension required prior to the actual grindingprocess. Furthermore, the outer bearing rings provided with notchesarranged in those areas from where the joints are to start and in whichthey are to end. After producing the joints by applying pressure theouter bearing ring 4 is hardened and then ground to itsfinish-dimension. Then the outer bearing ring 4, with one of the notches33, 34 is placed on to the blade of a tool, with pressure being exertedon to it or rather its outer circumference. This pressure presses theouter bearing ring 4 from its round shape into a shape deviating fromthe round one, with the pressure being applied for long enough and in amagnitude to ensure that the limit of elastic deformation of the outerbearing ring 4 from its round shape is exceeded causing it to be brokenapart in the region of the intended joints 24 or 24 and 25. In case thejoint 24 extends through the bearing track 6 of the outer bearing ring4, the breaking process has to be followed by precision machining,especially honing.

Bearing assembly for a wheel of a motor vehicle

    ______________________________________                                        LIST OF REFERENCE NUMBERS                                                     ______________________________________                                        1         wheel hub                                                           2         wheel flange                                                        3         inner bearing ring                                                  4, 4a, 4b outer bearing ring                                                  5         track of the inner bearing ring                                     6         track of the outer bearing ring                                     7         holding ring                                                        8         cage                                                                9         seal                                                                10        sealing cap                                                         11        wheel carrier                                                       12        bord step in wheel carrier                                          13        outer joint part                                                    14        assembly bolt                                                       15        fixing bolt                                                         16        through-bore for fixing bolt in outer bearing ring                  17        stop face in holding ring 7                                         18        inner face of holding ring                                          19        outer face of outer bearing ring                                    20        rolling number                                                      21        clamping ring                                                       22        driving joint                                                       23        teeth                                                               24, 25    joint                                                               26        through-bore for fixing bolt in clamping ring                       27        through-bore for fixing bolt in holding ring                        28        bore for assembly bolt                                              29        threaded bore in wheel carrier                                      30, 31    radial face of outer bearing ring                                   32        sealing ring                                                        33, 34    notch                                                               x-x       axis of rotation                                                    E-E       dividing plane                                                      A         axial extension of the bearing ring                                 y-y       radial plane                                                        35        holding bolt                                                        36        bore                                                                ______________________________________                                    

What is claimed is:
 1. A bearing assembly or a drivable wheel hub at anassociated wheel carrier of a motor vehicle, comprising:a double-rowrolling element bearing having an outer divided bearing ring provided soas to be fixable to the wheel carrier, and an inner single-part bearingring arranged so as to form one unit with a wheel flange or attachingthe vehicle wheel, the outer bearing ring (4) being divided by beingbroken apart in an area (24) of its circumferential extensionessentially in a plane (E - E) which extends radially relative to itsaxis (X - X), the inner bearing ring (3) being integral with a component(13) of a driving joint (22) provided for driving the vehicle wheel orconnected to the component (13) via teeth (23); a holding ring 7arranged so as to receive the outer bearing ring 4; and wherein theholding ring (7) has a radially extending stop face (17) arranged so asto contact a corresponding radial face (31) of the outer bearing ring(4), and an inner face (18) arranged so as to receive and outer face(19) of the outer bearing ring (4).
 2. A bearing assembly according toclaim 1, wherein the inner face (18) of the holding ring (7) covers onlypart of the axial extension (A) of the outer face (19) of the outerbearing ring (4).
 3. A bearing assembly according to claim 1, whereinthe holding ring (7) and the outer bearing ring (4) are connected toeach other by assembly bolts (14).
 4. A bearing assembly according toclaim 1, wherein at least one of the outer bearing ring (4) and theholding ring (7) are connected to the wheel carrier (11) by fixing bolts(15).